Oil Leak V6 TDI: Causes & Fixes

Hello guys,

Perhaps someone else has experienced this problem or can offer me some advice. Lately, my V6 TDI engine (AKN) has been losing more and more motor oil.

"There are increasingly large oil stains under the car. My initial suspicion was a leak in the oil pan. I started investigating the cause and discovered that the oil seems to be coming from above and running down the back of the engine."

There's oil leaking in the area between the two cylinder banks. I wiped it up once, but after a test drive, there was a lot of oil again.

What could be the problem? Could the lower seal on the oil filter housing be damaged? Has anyone else experienced this issue before?

I am grateful for any advice.

Regards,
AL

Hello,

It's always difficult to determine the source of a draft because of the wind during travel, unless you verschandeln everything and take a short trip around.

I had the same problem after removing my head cover. In my case, it was a leak in the needle lifter housing. After cleaning everything thoroughly and applying sealant to the passages (including the blue semi-circles), everything was sealed again.



But did you already do the pressure test on the oil separator?

Greetings.

Rainer.

Hi,

Okay, so it's not the valve cover gaskets; I checked them, and they are completely dry all around. I replaced them a year ago.

But what do you mean by "pressure test of the oil separator"?

Best regards.
Sure, here is the translation of the text from German to English:

"Al"

If a pressure gauge is connected to the oil level indicator pipe, it should not measure more than 5 mbar with the engine running. Otherwise, the oil separator for the crankcase ventilation system is clogged or defective.

If you don't have a pressure gauge, you can also unscrew the oil filler cap while the engine is running. If you hear hissing, the oil separator is sealed. However, it's possible that the overpressure is so low that you won't hear it, but in that case, I doubt the oil would spray out vigorously...
"By the way, have you ever checked what the oil return line from the turbocharger to the engine block looks like? Something leaked out of mine once, and suddenly there was no more oil in the engine..."

Okay, I just did a quick check. The engine wasn't really warm yet, but when I unscrewed the oil cap, there was a noticeable hissing sound, so there seems to be some pressure behind it. However, I can't tell right now if that's normal or not.

I've taken a closer look at the engine now. It seems that the oil is leaking somewhere in the area of the oil filter housing. The turbocharger hoses are dry.

Regards,
Sure, here is the translation of the text from German to English:

"Al"

Hello,

The seals on the cylinder head cover are leaking at the injector bore holes. Are these seals available individually from a parts supplier, or would they rather sell me two complete cylinder head covers?

Otherwise, I replaced the KGE filter as a precaution, but it didn't reduce the oil leak.

Best regards, René.

Hello,

ich kann nur noch aus vergangener Erfahrung mit meinem V6 TDI (allerdings der AFB) berichten, das er zum Schluss auch stark geölt hat. Es kam aus alle möglichen Dichtungen. Es fing ganz harmlos an. Zuerst kam aus einer Düsen-Dichtung ganz wenig raus, es war leicht 'verschwitzt'. Irgendwann kam noch eine weitere Düse auf der anderen Zylinderbank dazu. War soweit noch nicht weiter schlimm. Einestages bemerkte ich unter dem Auto einen Ölfleck. Aus Panik machte ich mich auf die Suche der Ursache. Unter der Motorabdeckung sah das ganze zwischen den Zylinderbänken nicht mehr toll aus. Es stand eine regelrecht Pfütze da drinnen. Desweiteren kam Öl aus der Kabeldurchführung vom NHG, aus den Ventildeckeldichtungen und aus dem Deckel vom Ölfilter. Es lief überwiegend auf der Seite der LiMa runter, verteilte sich über sie und wurde durch den Fahrtwind unter dem ganzen Motorblock verbreitet. Ich fuhr zum freundlichen und ließ meine Kurbelgehäusedruck prüfen. Dieser war über 5mBar allerdings nicht so stark erhöht wie ich erst annahm. Lag um die 10-15mBar. Ich ließ in meiner freien Werkstatt die Kurbelgehäuseentlüftung wechseln und eine gründliche Motorwäsche (oben und unten) machen so das er wirklich überall ölfrei war. Siehe da, nach der ersten Probefahrt über rund 100km im oberen Bereich (Ventildeckeldichtung und Düsendichtung) wieder fast alles trocken. Die ersten drei Tage auch keine Flecken mehr unter dem Auto. Aber leider freute ich mich zu früh, es kamen wieder Flecken. Sogleich schaute ich mir oben alles an. Aber es war weiterhin so gut wie trocken. Von unten sah es allerdings anders aus. Ölwannendichtung der unteren und der oberen Ölwanne waren undicht. U'And my mechanic said it looks like something is damp further up [possibly the oil pump?!].'
As a result, the car was no longer sufficient for my needs, and I sold it partly because of this defect. Replacing the seal on the upper oil pan is actually not an easy or inexpensive task!
I suspect that the excessive crankcase pressure destroyed the sealant of the oil pan, causing it to start leaking. It's almost like trying to fill a bottomless pit to get a V6 engine completely leak-proof again... if that's even possible .

I wish you good luck and success. *fg*

Regards,

DENNIS

PS: Now I'm driving another 'small' ASZ and I'm currently experimenting with a resistor instead of the diesel temperature sensor.

That doesn't sound great at all; I don't think an oil filter housing is exactly a bargain.

I'll take everything apart and analyze it next weekend.

Regards,
Sure, here is the translation of the text from German to English:

"Al"

Don't quote me on this, but I think the oil filter housing probably costs around 120 euros.

The car was brought to our workshop, and there was no oil visible on the dipstick. It wasn't easy to locate the leak. At first glance, I would have suspected the turbocharger. The entire top part of the engine was covered in oil. There was about a liter of oil in the crankcase. So, we cleaned it up, refilled the oil, and started the engine. Afterwards, it became very clear that the oil was leaking out from under the oil filter housing. When we turned off the engine, there was some gurgling and bubbling coming from that area.

The ultimate cause was a loose screw and a broken seal. However, the entire housing was replaced as a preventative measure. This proved to be justified later on, upon closer inspection. A hairline crack had formed around the loose screw, which was barely visible.

The kind man was visibly relieved that this problem could be resolved so affordably, as he had already expected a complete engine failure.

Make sure to follow the steps in order before you see black.

- Measure the crankcase pressure; if it's too high, replace the component.
( https://community.dieselschrauber.org/en/viewtopic.php?p=65042#65042 )
- verschandeln the engine properly.
- Take a longer test drive.
- After an oil spill, monitor the area.
- Seal any leaks.
If you've been dealing with excessive crankcase pressure for a long time, it's likely that the oil pan and engine block need to be resealed. Unfortunately, it can be quite a delicate job.

Best regards, Manuel.

PS: When installing a heat pump system, be sure to include the 'B' variant -> it will ensure long-term reliability.
Changing gears for the first time, approximately 3 hours.

Okay, so I ordered a new crankcase ventilation system yesterday. I hope it's the solution. The crankcase pressure is definitely too high for me right now. When I open the oil filler cap with the engine running, it makes a hissing sound.

Now I've also figured out where the oil is coming from. There's an aluminum pipe running from the turbocharger to the engine block (the one that looks like an accordion at the bottom), and the oil is leaking from the connection there.

Let's see if things get better with the new energy contract.

Regards,
Sure, here is the translation of the text from German to English:

"Al"

Yesterday I replaced the oil separator and also changed the seal on the turbocharger's oil return line.

It was a straightforward fix. The built-in oil separator was completely sealed. Now, with the new one installed, the high crankcase pressure is definitely gone. I'll now see if this stops the oil leak...

Regards,
Sure, here is the translation of the text from German to English:

"Al"

Okay, I've been driving for about a week now. The engine is completely dry again. Thanks to everyone for the tips.

Regards,
Sure, here is the translation of the text from German to English:

"Al"